Charging rate on a 1993 75 hp Mariner OB

[Big Buck Buster]

I posted this question in my other topic, but thought it might help to put it in a new one.

What is normal charging rate on this motor application?

I just put a new rectifier in tonight. The tachometer is now working, and the system is charging.

At idle the voltage gets up to 15.96 volts.

Is this normal?

[boatfixer]

Can you provide the serial number? I'm trying to figure out if yours has a separate regulator. That does seem high, especially at idle. After I replaced the stator in my Dads 90, I was getting 15+ at around 2000 rpm.

[Big Buck Buster]

Here it is:

OB248946

[Big Buck Buster]

Found this while doing a search for parts. I am going to assume that it does have a voltage reg on it. Pretty pricey too, at $186.00. (#44)

[boatfixer]

I would be curious if voltage continued to climb as you increased rpms. Also make sure the regulator has a good clean ground. Yes 44 is the reg.

[Big Buck Buster]

I just thought that, after posting the pic of the parts, to take a look at my motor. I couldn't find anything on the motor that resembled #44 in the diagram. Hmmm. I don't know if that is on my motor.

[boatfixer]

Does it have the small square rectifier with 3 studs or are the wires already attached?

[Big Buck Buster]

Does it have the small square rectifier with 3 studs or are the wires already attached?

Small square with three studs.

Is there more than one option with this same motor?

[boatfixer]

If you have the small one then that is a rectifier only. Follow the wires to the regulator.

[Big Buck Buster]

If you have the small one then that is a rectifier only. Follow the wires to the regulator.

The yellow wires on the rectifier go up to the flywheel.

[Big Buck Buster]

The rectifier that the merc dealer sold me matched the one I removed. Part number on the rectifier is 816770. If that helps any?

[boatfixer]

Does the red wire go to the solenoid then? If so, there is no regulator and voltage is "regulated" by the battery condition. You must be sure it is full of water and do not use a gell type battery or AGM battery

[Big Buck Buster]

Does the red wire go to the solenoid then? If so, there is no regulator and voltage is "regulated" by the battery condition. You must be sure it is full of water and do not use a gell type battery or AGM battery

Yes,

The red goes to the solenoid right above the rectifier.

It is not a gell battery. I will have to check the water tomorrow.

The battery was stamped out 08. I know this doesn't mean much.

What would be a good recommendation for a starter battery for this motor, if I have to replace it?

[boatfixer]

Any average run of the mill group 24 marine battery. I would check the water and clean all connections first. If the voltage doesnt climb higher than what youve decribed, I wouldnt really be concerned.

[Big Buck Buster]

Thanks for all the help.

I will check all that tomorrow after work. I do have an extra starting battery in the garage, if needed.

BBB

[Big Buck Buster]

Any average run of the mill group 24 marine battery. I would check the water and clean all connections first. If the voltage doesnt climb higher than what youve decribed, I wouldnt really be concerned.

Got back to the boat tonight after work. Checked the battery. It was an Everstart sealed marine starter battery. Disconnected it, cleaned the cable ends, put my other battery in. Fired it up, and low and behold, the charging rate at idle was at 14.3 volt to 14.7. Raised the idle a little, and the voltage went up to 15.3 to 15.7. Let the idle back down again, back down to the 14.3 to 14.7.

Thanks for the heads up on the battery possibly being it. It was either the connections, or the battery. Didn't have to clean the connections very much, so my guess would be the battery.

I might put the other battery back in tomorrow to see it the volts go back up.

BBB

[boatfixer]

Glad to hear that BBB